The present invention relates to ophthalmic devices. More particularly the invention is directed to composite ophthalmic devices.
The use of various ophthalmic devices, such as contact lenses and corneal implants, are known for the correction of vision abnormalities. Such ophthalmic devices typically are designed to correct one abnormality, e.g., myopia, and made from one optical polymeric material. There have been attempts to produce composite contact lenses having more than one polymeric material. Composite contact lenses having a relatively hard center section circumscribed by a soft and wettable edge section have been disclosed by various publications. The soft and wettable edge section of the lens is designed to provide improved comfort on the eye, thereby reducing the eye irritation often experienced by hard contact lens users. Additionally, there have been attempts to produce bifocal rigid contact lenses having two optical materials having different indices of refraction. Such attempts typically produce a composite lens by laminating or cementing two separately produced, e.g. lathe formed, component lenses. However, the cementing approach requires perfectly or near perfectly matching component lenses to produce the composite lens. In addition, the process for separately producing component lenses and the process for precisely cementing the component lenses are labor intensive and time consuming and are not conducive to mass producing bifocal lenses. Moreover, the cementing process is not highly suitable for producing hydrogel contact lenses since typical hydrogel contact lenses are formed in a dehydrated state and subsequently hydrated. When a hydrogel lens is hydrated, the lens swells and changes its dimension. Consequently, a composite hydrogel lens additionally experiences optical distortion and delamination problems.
There remains a need for composite lenses that can be produce with a production process that is simple and can easily be used to mass produce such lenses.
There is provided in accordance with the present invention a molded ophthalmic lens having a first optical component and a second optical component, wherein the first optical component is cast molded to encapsulate the second optical component such that the first optical component provides an optical function and the second optical component provides an additional optical function. The term xe2x80x9coptical functionxe2x80x9d is used hereinafter to indicate both optical and ophthalmic functions, unless otherwise indicated. Desirably, the first optical material is a polymerizable or crosslinkable material that does not significantly shrink while being cured. More desirably, the first optical material is a polymerizable or crosslinkable material that does not significantly shrink or expand while being cured and processed thereafter.
The invention additionally provides a process for producing a molded composite ophthalmic lens. The process has the steps of providing a pre-lens, which is formed from a first optical material, wherein the pre-lens is a cured product of a curable first optical material and the pre-lens has an upper surface and a lower surface; providing a second optical material on the upper surface; placing an amount of the first optical material such that the second optical material is encapsulated by the pre-lens and the first optical material; and curing the first optical material encapsulating the second optical material in a finishing mold assembly, thereby affixing the second optical material and cast molding the ophthalmic lens.
The composite ophthalmic lens of the present invention is highly suitable for providing more than one optical and/or ophthalmic functions. Unlike prior art composite lenses, the ophthalmic lens can be produced conveniently using an insert molding process, which is a modified cast molding or double side molding process. The present molding process provides a fully formed composite lens, and therefore, the molded lens does not require additional handling and can be mass produced. In addition, the molding process is particularly suitable for producing soft hydrogel composite lenses having more than one optical or ophthalmic functions.